CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOW - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities:
Net loss	$ (33,261)	$ (80,924)
Adjustments to reconcile net loss to net cash used for operating activities:
Depreciation and amortization	823	1,079
Amortization of debt issuance costs and discounts	13,860	12,761
Amortization of discount or premium on available-for-sale securities	700	1,940
Share-based compensation expense	1,740	3,032
Inventory impairment charge		29,522
Changes in assets and liabilities:
Accounts receivable	(1,298)	(3,299)
Inventories	2,343	(4,113)
Prepaid expenses and other assets	4,206	3,611
Accounts payable	(620)	(2,908)
Accrued and other liabilities	(7,227)	(2,563)
Deferred revenue	67,323	781
Net cash provided by (used for) operating activities	48,589	(41,081)
Cash flows from investing activities:
Property and equipment purchases		(310)
Purchases of available-for-sale securities	(50,523)	(176,510)
Proceeds from maturity of available-for-sale securities	60,050	219,500
Proceeds from sale of Available-for-sale Securities	6,960
Net cash provided by investing activities	16,487	42,680
Cash flows from financing activities:
Repayments of note payable	(6,359)	(5,402)
Sale of common stock through employee stock purchase plan	25	125
Net cash used for financing activities	(6,334)	(5,277)
Net increase (decrease) in cash and cash equivalents	58,742	(3,678)
Cash and cash equivalents:
Beginning of period	95,395	83,174
End of period	$ 154,137	$ 79,496